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Notholaena standleyi is one of the most striking ferns of Mexico and the southwestern US (Arizona, Colorado, New Mexico, Oklahoma, Texas). It is locally common in rock cracks and sheltered pockets under boulders in dry exposed sites. Along with Astrolepis spp., N. standleyi is perhaps the most xeric-tolerant of all ferns. The farina composition (and color) varies considerably within this species. Seigler and Wollenweber (1983) distinguished three “chemotypes”—groups within N. standleyi that differ in farina composition, geographic range, and substrate preferences—and Windham and Yatskievych (unpublished data) distinguished a fourth. These four chemotypes (informally referred to as Gold, Pallid, Yellow, and Yellow-Green) also differ in their ploidy levels (number of complete chromosome sets they contain). Gold and Yellow are diploids, while Pallid and Yellow-Green are tetraploids (Windham and Yatskievych, unpublished data). Preliminary data (Rothfels et al., 2008) suggest that these four chemotypes may be phylogenetic units worthy of taxonomic recognition, but more study is needed.
Farina composition and color vary considerably within Notholaena standleyi. The leaves in this photograph probably represent the Gold chemotype (left) and Yellow chemotype (center and right). They are from one of very few known mixed chemotype populations. © 2008 Carl Rothfels